A determination of an angle (azimuth and/or elevation) has long been one of the unique functions of many radar systems. Because of this, numerous methods are known which can be used to determine the angle in this manner. Essentially, there are two different approaches. According to the first approach, the lobe of a sending antenna and a receiving antenna of the radar system is rotated mechanically or electronically on the plane of the angle being sought. This makes it possible to determine the location or angular position of the radar target detected based on the position of the antenna lobe at the time that an echo signal is recorded. According to the second approach, echo signals of detected radar targets are recorded over multiple antenna lobes of a multibeam radar system, and the angular position of the radar target is determined by analyzing the echo signals obtained from the individual antenna lobes. The monopulse method is one known example of this second approach. With this method, echo signals are recorded simultaneously over two antenna lobes, and the angle of one radar target is determined on the basis of an amplitude and/or phase difference in the echo signals recorded over the separate antenna lobes. A radar system with this type of angle analysis is described, for example, in European Patent Application No. 0 766 100. A device for determining an angle of incidence of recorded radar signals is also described in U.S. Pat. No. 4,320,400, with the angle of incidence here also being determined on the basis of an amplitude and a phase comparison between radar signals that were recorded over multiple antennas.
A method that differs from that described in these documents, but which still falls under the second approach, is described in International Patent Publication No. WO 97/20229, according to which, in a radar system which is used in particular in motor vehicles, the angle in which a detected radar target is located is determined by recording the echo signals of the radar target (whose amplitudes are normalized) via at least two receiving channels and comparing them to stored normalized values of a two-way antenna pattern of the radar system. An important advantage of this method over the method described above is that it eliminates the need for precisely symmetrical antenna lobes, since this method does not compare the received signals with each other, but instead compares the received echo signals to stored reference values. This reduces the effort and therefore, of course, also the costs of producing this type of radar system. However, it has been demonstrated that, in the case of angular positions in which nulls appear in the antenna pattern of the receiving elements, ambiguities in determining the angle can be avoided only with additional effort. This additional effort involves making the nulls less pronounced by "deforming" the antenna pattern. However, this effort is also associated with a lower overall antenna gain.